SolidWorks refers to the "parametric" solid modeller employed for 3-D design. By calling it Parametric, we mean that the dimensions can have relationships with one another and can be altered at any point during the design process to automatically adjust the solid part and any related documentation (blueprint). AutoCAD, on the other hand, is mostly a 2-D design tool with limited 3-D capabilities.

SolidWorks is a 3D mechanical CAD program that you can use on Microsoft Windows; the files in SolidWorks are based on the Microsoft Structured storage file format. There are a number of files embedded within each SLDASM (assembly files), SLDDRW (drawing files), and SLDPRT (part files), with metadata sub-files and preview bitmaps. You can use third-party tools to extract these sub-files, but the sub-files most often employ proprietary binary file formats.

SolidWorks is a solid modeller that is parasolid-based; it employs a parametric feature-based approach when it comes to putting together models and assemblies. Parameters refer to restrictions, the values of which determine the model’s shape or geometry. These Parameters can be numeric, in the form of circle diameters, line lengths, or geometric, like tangent, concentric, parallel, vertical or horizontal. To capture design intent, you can employ relations to associate numeric parameters with each other.

Like SolidWorks, AutoCAD is also a Computer Aided Design application for 2D/3D design and drafting. AutoCAD was one of the earliest CAD programs that arrived for use in Personal Computers, at a time when CAD programs typically ran on mainframe computers. In its early versions, AutoCAD made use of basic entities like lines, circles, poly-lines, arcs, and text to put together more complex objects. AutoCAD has ever since started to support custom objects via its C++ Application Programming Interface (API).

Today, AutoCAD comes with an entire set of basic solid modelling and 3-D tools. After the release of AutoCAD 2007, users were able to get better navigation for working in three dimensions and editing 3D models. Quality renderings are now easier to accomplish, thanks to the inclusion of the mental ray engine in rendering. Network modelling and parametric functionality were made available in AutoCAD 2010. As of now, you can run AutoCAD only on Windows operating systems. AutoCAD can work on an emulator or compatibility layer like VM-ware Workstation, although some performance issues can surface while working with large drawings or 3-D objects. You can pick either AutoCAD or SolidWorks based on what you want to accomplish. Usually, SolidWorks is preferred for 3 dimensional designs whereas AutoCAD is more appropriate for 2D design.